Author
Topic: Another Mod... (Read 36800 times)

Smokeitall... definitely not an engineer. The last 25 years I've owned a general insurance brokerage. Prior to that I was a service mechanic and before that I was in construction. I've always enjoyed working with my hands from building furnature to cars and boats. A few winters ago I tore into my sons Jeep YJ. I put 8 inches of lift in it, 33 inch tires, 411 gears front and back, disc brakes all around, rear diff our of an explorer, GM HEI ignition, carb mods.......................................

........................................................................................... then he sold it!

My Bradley is a 4 rack digital unit. It is controlled by a PID and I have a circulation fan installed. I also have the unit installed in my heated garage and vented so the ambient temp is 65 degrees ( with no wind ). I have my TC for the PID mounted to the back of the cabinet between the 2nd and 3rd rack (counting from the bottom). The TC bracket holds the TC off the back wall by about 3/4". I also have my smoke generator in a permanent offset installation.

Ok... I turned the unit on and preheated to 200 degrees, vent wide open, while I got 6 racks of ribs ready. I removed the membrane, cut each rack in half and applied my rub. This fills 4 Bradley racks with 3 half racks of ribs on each Bradley rack.

I took my time putting them into the smoker and setting up the Maverick temp probes for the test so by the time I got the door shut I was down to 131 degrees on the PID. I put the Maverick temp probe directly below the very bottom rack because I wanted to track the temps the lowest rack was being exposed to during this test. I left the vent wide open. Within 5 minutes the temps were climbing.

15 minute mark... PID at 150, Bradley at 170, Maverick at 210.

30 minute mark... PID at 174, Bradley at 194, Maverick at 237.

45 minute mark... PID at 190, Bradley at 207, Maverick at 244.

1 hour mark... PID at 200, Bradley at 210, Maverick at 250.

As the temps stabilized in the cabinet and the ribs started to gain some temp the deference between the Maverick under the lowest rack and the PID became a lot closer, typically around 10 degree difference.

Certainly doing a higher preheat would have also helped. I typically do preheat to about 260 but during the test I just wanted to see how it would recover without a higher preheat.

I tried twice to run the auto tune on the PID and I now have it close (2 degree temp swings each side of set point) but I will continue to try to get it dialled in a little closer.

I haven't decided yet but I may move my TC between the lowest rack and the second rack. This would further close the gap between the Maverick and the PID. I could even put it just below the lowest rack but I would like to have a happy medium of keeping the temp of the upper racks close to the target temp as well with a full load.

Just as a disclaimer...I have been speaking with Bradley about this. More specifically about the rating of the insulation in the Bradley. They are going to get back to me on the specifics and I will let you know. My thought on the "risk" of higher temps are... the only part of the tower that will be exposed to higher heat will be the rear of the cabinet directly behind the elements. In addition the only time it will be exposed to higher heat is when you are trying to bring the cabinet back up to temp after loading. Once the set temp has been achieved the cabinet really isn't exposed to any higher heat than with a single element. Depending on the ratings of the factory insulation a possible solution would be to re-insulation the rear of the cabinet with the same insulation (Roxul Mineral Wool) that I used in the smoker I built. The Mineral Wool is rated at 2100 degrees so using it in a smoker is not a problem.

I know Beefman has been operating with the 900 watt finned strip heater mod for over a year now with no problems so I will wait to see what I hear from Bradley, then make a decision on it.

Overall the test went very well. To say the least the temp recovery is "extremely" improved. I'll keep you all posted.

Mike

PS - I'm whispering this...I used mesquite on the ribs, In fact I tried it on some Canadian bacon last week and loved it... go figure!

this sounds like a very good mod. any chance chance you measure the Amp addition to this. I have a 10 amp switch on my system that I want to be careful about.

But as far as the element brightness. I had to replace my original a few weeks ago due to a power fried issue on the previous one. The new one burned much brighter than the original. And actually the heat was much nicer than the original. My cost was a but more for the replacement, I did the ceramic items, heat shield and bulb. Just over $20 but got my issues resolved.

To figure the amps you divide the wattage of the burner by the supply voltage and this gives you the amps. With this mod you have two 500 watt burners wired in parallel/1000watts divided by 120 volts= 8.33 amps.

OK, just gotta ask--on a 4 rack, wouldn't the probe be in the same place counting from top or bottom?

Seriously, this looks like a great mod. When I put a few sticks of summer sausage in mine, the temp takes a while to come up. And to make things worse, in a few years I'll be living in the upper midwest, so more heat will be nice. I'll keep track of this idea for sure. get smokindrano

Wild_man is exactly right... 8.33 amps... I was running an 8 amp fuse in my PID and I switched it to a 10 amp fuse and had no problems.

Drano

I'm not sure but I think you are referring to my placement of my TC for my PID as compared to the placement of the temp probe from the factory on the DBS. If so you are correct, it is in a similar location but I'm considering relocating it to balance temps better.

It looks good. I also have one question. Is there a way to setup a switch on the second element, so that you can turn it on/off on demand? For example if I'm smoking sausage or fish and I don't need the extra heat; can a toggle switch be added to turn on/off the second element?

I certainly don't see why you couldn't wire a switch into it. It would just require a little more wiring and a decision on where you want the switch.

Having said that I'm not sure it would be any advantage because the PID is controlling it anyway. Having more heat available (larger heater) just means at lower temps the PID will not run the heaters as long and probably not at full power. The other thing you would have to do is change the PID parameters if you were using the 2nd heater or not.

As you know I have a DBS. The heating element in the DBS is wired directly to the plug in the back of the tower, except there is a high temp fusable link in it.

The OBS, to my knowledge, is wired to the slider control. In my mind this mod will require taking the temp slider out of the circuit or at least thats how I would do it because there is no way to tell if the slider control would take the added draw of the 2nd heater. Mind you, if you took the power for the 2nd heater directly off the plug on the back of the OBS you would end up with the 2nd heater being powered direct and the original heater still running through the slider control. Personally, on the OBS I would just rewire both heating elements direct from the plug on the back of the tower and eliminate the temp slider from the circuit altogether.

I certainly don't see why you couldn't wire a switch into it. It would just require a little more wiring and a decision on where you want the switch.

Having said that I'm not sure it would be any advantage because the PID is controlling it anyway. Having more heat available (larger heater) just means at lower temps the PID will not run the heaters as long and probably not at full power. The other thing you would have to do is change the PID parameters if you were using the 2nd heater or not.

Mike

Good point about the temperature controller. I have the DigiQ II, so switching from one to two elements wouldn't be a problem.

I tried twice to run the auto tune on the PID and I now have it close (2 degree temp swings each side of set point) but I will continue to try to get it dialled in a little closer.

I haven't decided yet but I may move my TC between the lowest rack and the second rack. This would further close the gap between the Maverick and the PID. I could even put it just below the lowest rack but I would like to have a happy medium of keeping the temp of the upper racks close to the target temp as well with a full load.

Could you post your new PID settings when you are done. I have a 6 rack digital with a PID, so before i do the Auto Tune do I need to have all 6 racks loaded or does it not have to be that big of load?